What is the meaning of не-?

A prefix used to derive negative senses.

A prefix used to derive indefinite forms of interrogative adverbs, determiners, and pronouns.

Prefix to create a negative meaning. Akin to un-, non-, im-, ir-.

un-, non-, in-, im-, ir-, dis-, mis- (not)

Prefix prepended to adjectives to create an adjective denoting a negative meaning (не (“not”)). Akin to un-, non-, im-, ir-.

Prefix to create a negative meaning: un-, non-, in-, im-, ir-, dis-, mis-

Source: wiktionary.org